IssueTracker

Yeah it randomly stops without a way to restart.  I get partially restored apps notification

This is quite easy to reproduce with 4G devices and also happens with 3G devices.
Here is what we see.

Purchase phone1. Put SIM in it / Or activate it other way.
Start using it as personal phone. Download bunch of APPs from markets. Set personal wallpapers.
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Now purchase brand new phone2. Same company/same model. doesn't really mater.
Put your working SIM from phone1 to Phone2.

Login using same google account.

Wait for few hours / days. If you are lucky, APPs that you dwonloaded may restore. But most of the time they are not. Alsow wallpaper never restores.

I tried this in DroidX2, Droid3, HTC Thunderbolt, Samsung Charge. Every where, its getting reproduced.

Based on log analysis, we found following:

when the restore function attempts to restore applications via the GMS vending app (market), there is an uncaught exception and it crashes (hence no apps restored).

Not sure what google is doing about this.

As I understand the backup mechanism is not triggered instantaneously. So a backup can happen anytime between 0-8 hrs according to my experience. The reason why you see the restore happening sometimes is because of this behaviour.